Plugins cause GHC to panic: cannot find dynamic libraries

With GHC 8.6.1 on Windows 7 x64, I seem to be getting a similar problem as in ticket #15492 (closed). Trying to use any type-checking plugin at all causes an error. Here with the natnormalise plugin:

ghc.EXE: panic! (the 'impossible' happened)
  (GHC version 8.6.1 for x86_64-unknown-mingw32):
        mkPluginUsage: no dylibs, tried:
C:\Code\Haskell\dylibs_bug\.stack-work\install\df4dd97d\lib\x86_64-windows-ghc-8.6.1\libHSghc-typelits-natnormalise-0.6.3-2vTVlu0GX1Q1cNTbomjNL6-ghc8.6.1.dll
C:\Users\Sam\AppData\Local\Programs\stack\x86_64-windows\msys2-20180531\mingw64\bin\libHSghc-typelits-natnormalise-0.6.3-2vTVlu0GX1Q1cNTbomjNL6-ghc8.6.1.dll
C:\Users\Sam\AppData\Local\Programs\stack\x86_64-windows\msys2-20180531\mingw64\lib\libHSghc-typelits-natnormalise-0.6.3-2vTVlu0GX1Q1cNTbomjNL6-ghc8.6.1.dll

  GHC.TypeLits.Normalise
  Call stack:
      CallStack (from HasCallStack):
        callStackDoc, called at compiler\utils\Outputable.hs:1160:37 in ghc:Outputable
        pprPanic, called at compiler\\deSugar\\DsUsage.hs:179:15 in ghc:DsUsage

That's with stack. I also checked with Cabal 2.4.0.1 to make sure, and indeed I get:

ghc.exe: panic! (the 'impossible' happened)
  (GHC version 8.6.1 for x86_64-unknown-mingw32):
        mkPluginUsage: no dylibs, tried:
C:\Users\Sam\AppData\Roaming\cabal\store\ghc-8.6.1\ghc-typelits-_-0.6.2-faf29727b3dbdfa09cfb6f0c881a2a227b5d2bb0\lib\libHSghc-typelits-_-0.6.2-faf29727b3dbdfa09cfb6f0c881a2a227b5d2bb0-ghc8.6.1.dll
C:\Program Files\ghc\mingw\lib\libHSghc-typelits-_-0.6.2-faf29727b3dbdfa09cfb6f0c881a2a227b5d2bb0-ghc8.6.1.dll

  GHC.TypeLits.Normalise
  Call stack:
      CallStack (from HasCallStack):
        callStackDoc, called at compiler\utils\Outputable.hs:1160:37 in ghc:Outputable
        pprPanic, called at compiler\\deSugar\\DsUsage.hs:179:15 in ghc:DsUsage

No problems with GHC 8.4.3.

Trac metadata

Trac field	Value
Version	8.6.1
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
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